ADAS entomologist John Buxton spoke about an Horticultural Development Company-funded project into Bemisia in poinsettia being carried out by the Food & Environment Research Agency (FERA) and ADAS. He advised growers to apply preventive programmes on the presumption that Bemisia will strike.
"You have got to plan a programme to get control early," he said. "The way to cope with Bemisia in poinsettia is to assume it's coming in on the cuttings, so if you plan a controlled programme from the start you have a better chance of getting on top of it."
Growers were told to tackle impatiens downy mildew with the same ethos and Stockbridge Technology Centre science director Martin McPherson explained that protection was the way forward, rather than eradication.
He added that the source of the disease was still unknown and urged the industry to address product stewardship and establish who takes responsibility for the plant once it has left the nursery.
"We have made progress and quite a lot has been achieved, but the problem is that the disease is reflecting very badly on the industry as a whole for further sales of Impatiens," he said.
"We need to figure out how to control the disease once the plants have left the nursery and we need to consider the risk from wild or introduced Impatiens and whether they are susceptible to infection and providing a source in winter."
He said the origin of the disease still needed to be established and research was being done into the effect of oospores (resting spores) and whether they survived in the soil to infect replanted plants.